(a) Field of the Invention
The present invention relates generally to three-dimensional display system. More particularly, the present invention relates to three-dimensional display system of reflection-type.
(b) Description of the Related Art
Among the technologies that display three-dimensional image, IP(lntegral Photography) which uses a lens array was first proposed by Lippmann in 1908. IP has not attracted much attention due to the limitation of the image capturing and displaying device. Recently IP begins to be studied extensively with the development of the high resolution image capturing and displaying device.
FIG. 1 shows the basic principle of the IP. IP consists of two functional parts (pickup/display) as shown in FIG. 1. In pickup part, many perspectives (that are called elemental images) of the three-dimensional object from various directions which are formed by the elemental lenses that constitute the lens array are captured and stored by the image capturing device. In display part, the reverse process of the pickup is performed. That is, the elemental images that were stored by the image capturing device are displayed by image displaying device, and the rays from the elemental images retrace through the lens array to integrate the three-dimensional image at the position where the original three-dimensional object was.
FIG. 2 is a more detailed image that depicts the image reconstruction principle of the IP. The elemental images which are displayed on the image displaying device (FIG. 2(a)) are integrated by the lens array (FIG. 2(b)) around the image plane position (FIG. 2(c)) of the lens array. The depth of the three-dimensional image is adjusted according to the spacing between the elemental images and therefore three-dimensional image can be displayed.
While conventional IP using the film as the pickup and displaying device could not display animation, a developed IP using the charge coupled device (CCD) camera and flat display panel (such as liquid crystal display (LCD) or cathode ray tube (CRT)) can display three-dimensional animation as well as still three-dimensional image. FIG. 3 shows the setup of the IP adopting the CCD camera and LCD panel as the pickup and display device respectively.
Three-dimensional display based on the IP can display three-dimensional image without any viewing aids (such as glasses) and provides continuous viewpoints However, realization of large size three-dimensional display based on the IP is difficult because large size lens array which is a major component of IP can not be readily made.